Cylinder or engine blocks form part of an internal combustion engine and may include cylinder bores at least partially forming spaces into which pistons may be inserted. A cylinder head may be disposed above the cylinder block to form the cylinders, while a crankcase may be disposed below the cylinder block to support a crankshaft. The cylinder block may include a plurality of bulkhead inserts to provide support to the crankshaft via bearings, couple the cylinder head to the overall cylinder block, and increase the stiffness and structural integrity of the block.
U.S. Pat. App. No. 2010/0050977 describes the inclusion of crankcase inserts in an engine block comprised of magnesium alloy. The crankcase inserts may be comprised of compacted graphite iron (CGI) and inserted below and between a plurality of cylinder chambers. Each insert includes a plurality of upper coupling parts which extend outward from a rectangular body in a parabolic spoke-like configuration, and provide connection mechanisms by which the inserts may be coupled to the engine block. The inserts may undergo a splitting process in which they are bisected along a crankshaft insertion hole and resulting upper and lower portions are attached to each other following crankshaft insertion.
The inventors herein have recognized several issues with such an approach. First, the upper coupling parts may be limited in the amount of force they can support, due to their outwardly extending spoke-like configuration. Such extension further increases the volume and mass of the inserts. Moreover, spacing between adjacent cylinder bores in the engine block may be increased due to the volume occupied by the upper coupling parts. Finally, the spoke-like configuration may limit mitigation of cylinder bore distortion during engine operation.
Bulkhead inserts having a cracked cap and an improved structure for strength and stiffness are provided.
In one example, a cylinder block includes a plurality of cylinder bores, a crankcase disposed below the cylinder block in a vertical direction, and a plurality of inserts, where each adjacent pair of inserts of the plurality of inserts partitions each cylinder bore of the plurality of cylinder bores. Each insert of the plurality of inserts has an upper portion and a cap disposed below the upper portion, the cap cracked from the upper portion and rejoined to the upper portion by one or more fastening devices, the upper having one or more upper bosses, each upper boss having a surface with extruded, circumferentially-extending serrations. The plurality of inserts may be comprised of compressed graphite iron.
In this way, the overall weight of a cylinder block may be reduced, in turn improving fuel economy. The plurality of inserts may further facilitate a reduction in noise, vibration, and harshness, required machining, crankshaft weight, and a number of fastening devices needed to secure the inserts in the cylinder block.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.